Different types of car's headlight(1)

Halogen headlamp(car lamp housing)
Halogen lamp(car lamp housing) is actually a special kind of incandescent lamp. Its principle is that when there is current passing through the resistance, it will generate heat. When the temperature is high enough, it will emit blackbody radiation with the wavelength in the visible frequency band. There are generally two kinds of halogen lamps: iodine tungsten lamp and bromine tungsten lamp, and their principle is the same. When the incandescent lamp is on, although the filament temperature does not exceed the melting point and boiling point of tungsten, a small amount of tungsten will volatilize at high temperature. When the volatilized tungsten atoms encounter the colder bulb shell, they will condense and precipitate, and over time, a black tungsten film will be deposited on the bulb shell. This is why the shell of an ordinary incandescent lamp is blackened after a long time. If the bulb is filled with some iodine, when the bulb is lit, the iodine will volatilize into gas. When the iodine vapor meets the colder tungsten, it will react with it to form a compound with low boiling point - tungsten iodide, so as to volatilize the tungsten precipitated in the bulb shell. Tungsten iodide gas will decompose at high temperature. When tungsten iodide gas meets the filament, it decomposes and leaves tungsten on the filament, while iodine continues to dissociate between the filament and the shell in the form of gas. When it comes to the bulb shell again, it will react with the tungsten on the shell... In this way, on the one hand, the filament keeps volatilizing tungsten to the bulb shell, on the other hand, iodine keeps transporting tungsten back to the filament, In this way, the speed of filament volatilization consumption is greatly reduced and the service life of the bulb is prolonged. Thus, iodine tungsten lamps can be used to make incandescent lamps with high power, such as 1000 watts. If halogen is not added, if ordinary incandescent lamps achieve such high power, their service life will be very short and difficult to be practical. Halogen lamps have been widely used in the field of automotive lighting.

Xenon lamp(car lamp housing)
HID is the English abbreviation of high intensity discharge lamp(car lamp housing), which can be called heavy metal lamp or xenon lamp. Its principle is that it is filled with a variety of chemical gases in the UV cut anti UV crystal quartz glass tube, Most of them are inert gases such as xenon and iodide, and then pass through the supercharger (ballast) the 12 volt DC voltage on the vehicle is instantaneously boosted to 23000 volts. The xenon electrons in the quartz tube are excited by the high-voltage amplitude, and a light source is generated between the two electrodes, which is the so-called gas discharge. The white super electric arc generated by xenon can improve the color temperature of the light, which is similar to the sunlight in the daytime. The current required for HID operation is only It is 3.5A, the brightness is three times that of traditional halogen bulb, and the service life is 10 times longer than that of traditional halogen bulb. Xenon lamps have been widely used in the field of automotive lighting.